Re: [PATCH] generic/081: wait for lv to be settled before creating fs on it

[Dave Chinner <david@fromorbit.com>]

On Fri, Apr 03, 2015 at 05:41:15PM +0800, Eryu Guan wrote:
> Call 'udevadm settle' or 'udevsettle' or 'sleep 1' to make sure new lv
> is ready for use before making filesystem on it, depends on which
> command is available on the system.
> 
> Also sleep 1 before removing the test vg, as the snapshot may block the
> test vg from removal for a while.
> 
> Signed-off-by: Eryu Guan <eguan@redhat.com>
> ---
>  tests/generic/081 | 22 ++++++++++++++++++++++
>  1 file changed, 22 insertions(+)
> 
> diff --git a/tests/generic/081 b/tests/generic/081
> index e242c4c..8e1828b 100755
> --- a/tests/generic/081
> +++ b/tests/generic/081
> @@ -36,6 +36,9 @@ _cleanup()
>  	rm -f $tmp.*
>  	# lvm may have umounted it on I/O error, but in case it does not
>  	$UMOUNT_PROG $mnt >/dev/null 2>&1
> +	# fsync from xfs_io pins the snapshot in use for a while and blocks
> +	# vgremove, sleep 1 to avoid such failure
> +	sleep 1

Doesn't this indicate a bug in the LVM code? unmount flushes block
device caches, so there should be no IO remaining on the device
pinning it when unmount completes, right?

>  	$LVM_PROG vgremove -f $vgname >>$seqres.full 2>&1
>  	$LVM_PROG pvremove -f $SCRATCH_DEV >>$seqres.full 2>&1
>  }
> @@ -62,11 +65,30 @@ snapname=snap_$seq
>  mnt=$TEST_DIR/mnt_$seq
>  mkdir -p $mnt
>  
> +# use 'udevadm settle' or 'udevsettle' to wait for lv to be settled.
> +# newer systems have udevadm command but older systems like RHEL5 don't.
> +# But if neither one is available, just set it to "sleep 1" to wait for lv to
> +# be settled
> +UDEV_SETTLE_PROG="`set_prog_path udevadm`"
> +if [ "$UDEV_SETTLE_PROG" == "" ]; then
> +	# try udevsettle command
> +	UDEV_SETTLE_PROG="`set_prog_path udevsettle`"
> +else
> +	# udevadm is available, add 'settle' as subcommand
> +	UDEV_SETTLE_PROG="$UDEV_SETTLE_PROG settle"
> +fi
> +# neither command is available, use sleep 1
> +if [ "$UDEV_SETTLE_PROG" == "" ]; then
> +	UDEV_SETTLE_PROG="sleep 1"
> +fi
> +

This should probably go into common/config....

>  # make sure there's enough disk space for 256M lv, test for 300M here in case
>  # lvm uses some space for metadata
>  _scratch_mkfs_sized $((300 * 1024 * 1024)) >>$seqres.full 2>&1
>  $LVM_PROG vgcreate -f $vgname $SCRATCH_DEV >>$seqres.full 2>&1
>  $LVM_PROG lvcreate --yes -L 256M -n $lvname $vgname >>$seqres.full 2>&1
> +# wait for lv to be settled
> +$UDEV_SETTLE_PROG >>$seqres.full 2>&1

"# wait for lvcreation to fully complete"

Cheers,

Dave.
-- 
Dave Chinner
david@fromorbit.com